1. Field of the Invention
The present invention relates, in general, to the administration of oral anesthesia into a patient's mouth using a syringe, and, in particular, to lighting of the interior of a patient's mouth during the administration of oral anesthesia.
2. Information Disclosure Statement
It is well-known for dentists to use prior art oral anesthesia injection syringes, such as the prior art syringe shown in FIG. 1, to anesthetize a patient's mouth during dental surgery. A problem is that access to the inside of a patient's mouth is limited by the size of the patient's mouth opening, and it is difficult to adequately illuminate the inside of the patient's mouth so that the dentist can view the injection site during application of the anesthesia. Typically a light mounted on a movable arm is used to illuminate the inside of the patient's mouth, but the dentist's head and hands can impede illumination of the inside of the patient's mouth by the light. Also, when the dentist moves to various injection sites inside the patient's mouth, the light on the movable arm may have to be repositioned between injections so as to provide sufficient illumination inside the patient's mouth.
It is therefore desirable to have a light inside the patient's mouth that directly illuminates the desired injection sites as the oral anesthesia injection syringe is moved from one injection site to another. It is further desirable to provide a “hands free” means of lighting the inside of the patient's mouth that moves with the oral anesthesia injection syringe and that does not require an additional hand to manage the positioning of the lighting of the inside of the patient's mouth.
It is further desirable to provide a single-use disposable oral anesthesia injection syringe that illuminates the inside of a patient's mouth.
Furthermore, in a single use battery powered device such as an LED flashlight, once the light is activated, the battery begins to discharge and the LED emits less and less usable illumination with time. At some point, the light is too dim to be useful, and, for a single use device without an off switch, the LED would continue to glow dimmer and dimmer, likely for days after being discarded from use. It is desirable to incorporate a shut off device that would extinguish the LED completely at some diminishing point of its useful illumination, rather than allow it to glow ever more dimly for days until extinction.
Various battery technologies each have their own specific discharge characteristics. Some source current at relatively steady rates while their voltage decreases with time, while others may maintain a fairly steady voltage through their discharge curve as their ability to source current decreases with time. Because batteries utilize chemical reactions to generate power, they tend to exhibit a small amount of recovery in their output voltage and current capacity over time after being disconnected from their load. It is this small recovery characteristic which makes basic voltage or current sensing switches employed to disconnect, or turn off a load, tend to oscillate at a very low rate, or switch on and off again and again.
If a basic voltage or current sensing switch with typical hysteresis were used in the case of a single use flashlight, once the light became too dim to be useful, the switch would shut the light off and it would likely be set aside or perhaps discarded in the trash. Once disconnected from the load, the batteries would experience some recovery in their voltage and current capacity with time and turn the switch and the light on again. The batteries would then deplete again with time and switch off again after this. In essence, the light would blink on and off, again and again, as the batteries cycle through depletion and recovery cycles over and over. This cyclic process could continue for days until the batteries were finally depleted beyond their ability to generate visible illumination.
It is therefore desirable to utilize a device that would prevent this cyclic blinking behavior and positively extinguish the light permanently once it had gone dim past the point of useful illumination.
It is still further desirable to provide a single-use disposable oral anesthesia injection syringe that illuminates the inside of a patient's mouth, in which the illumination self-extinguishes after approximately ten minutes of use so that the apparatus may be discarded into a disposal container for hazardous biological materials without illuminating the disposal container.